using System;
using System.IO;
using System.Collections.Generic;

namespace PickGold.Zip
{
	public partial class ZipFile
	{
		/// <summary>
		///   Adds an item, either a file or a directory, to a zip file archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This method is handy if you are adding things to zip archive and don't
		///   want to bother distinguishing between directories or files.  Any files are
		///   added as single entries.  A directory added through this method is added
		///   recursively: all files and subdirectories contained within the directory
		///   are added to the <c>ZipFile</c>.
		/// </para>
		///
		/// <para>
		///   The name of the item may be a relative path or a fully-qualified
		///   path. Remember, the items contained in <c>ZipFile</c> instance get written
		///   to the disk only when you call <see cref="ZipFile.Save()"/> or a similar
		///   save method.
		/// </para>
		///
		/// <para>
		///   The directory name used for the file within the archive is the same
		///   as the directory name (potentially a relative path) specified in the
		///   <paramref name="fileOrDirectoryName"/>.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		///
		/// </remarks>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddFile(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.AddDirectory(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateItem(string)"/>
		///
		/// <overloads>This method has two overloads.</overloads>
		/// <param name="fileOrDirectoryName">
		/// the name of the file or directory to add.</param>
		///
		/// <returns>The <c>ZipEntry</c> added.</returns>
		public ZipEntry AddItem(string fileOrDirectoryName)
		{
			return AddItem(fileOrDirectoryName, null);
		}


		/// <summary>
		///   Adds an item, either a file or a directory, to a zip file archive,
		///   explicitly specifying the directory path to be used in the archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   If adding a directory, the add is recursive on all files and
		///   subdirectories contained within it.
		/// </para>
		/// <para>
		///   The name of the item may be a relative path or a fully-qualified path.
		///   The item added by this call to the <c>ZipFile</c> is not read from the
		///   disk nor written to the zip file archive until the application calls
		///   Save() on the <c>ZipFile</c>.
		/// </para>
		///
		/// <para>
		///   This version of the method allows the caller to explicitly specify the
		///   directory path to be used in the archive, which would override the
		///   "natural" path of the filesystem file.
		/// </para>
		///
		/// <para>
		///   Encryption will be used on the file data if the <c>Password</c> has
		///   been set on the <c>ZipFile</c> object, prior to calling this method.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		///
		/// </remarks>
		///
		/// <exception cref="System.IO.FileNotFoundException">
		///   Thrown if the file or directory passed in does not exist.
		/// </exception>
		///
		/// <param name="fileOrDirectoryName">the name of the file or directory to add.
		/// </param>
		///
		/// <param name="directoryPathInArchive">
		///   The name of the directory path to use within the zip archive.  This path
		///   need not refer to an extant directory in the current filesystem.  If the
		///   files within the zip are later extracted, this is the path used for the
		///   extracted file.  Passing <c>null</c> (<c>Nothing</c> in VB) will use the
		///   path on the fileOrDirectoryName.  Passing the empty string ("") will
		///   insert the item at the root path within the archive.
		/// </param>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddFile(string, string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.AddDirectory(string, string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateItem(string, string)"/>
		///
		/// <example>
		///   This example shows how to zip up a set of files into a flat hierarchy,
		///   regardless of where in the filesystem the files originated. The resulting
		///   zip archive will contain a toplevel directory named "flat", which itself
		///   will contain files Readme.txt, MyProposal.docx, and Image1.jpg.  A
		///   subdirectory under "flat" called SupportFiles will contain all the files
		///   in the "c:\SupportFiles" directory on disk.
		///
		/// <code>
		/// String[] itemnames= {
		///   "c:\\fixedContent\\Readme.txt",
		///   "MyProposal.docx",
		///   "c:\\SupportFiles",  // a directory
		///   "images\\Image1.jpg"
		/// };
		///
		/// try
		/// {
		///   using (ZipFile zip = new ZipFile())
		///   {
		///     for (int i = 1; i &lt; itemnames.Length; i++)
		///     {
		///       // will add Files or Dirs, recurses and flattens subdirectories
		///       zip.AddItem(itemnames[i],"flat");
		///     }
		///     zip.Save(ZipToCreate);
		///   }
		/// }
		/// catch (System.Exception ex1)
		/// {
		///   System.Console.Error.WriteLine("exception: {0}", ex1);
		/// }
		/// </code>
		///
		/// <code lang="VB">
		///   Dim itemnames As String() = _
		///     New String() { "c:\fixedContent\Readme.txt", _
		///                    "MyProposal.docx", _
		///                    "SupportFiles", _
		///                    "images\Image1.jpg" }
		///   Try
		///       Using zip As New ZipFile
		///           Dim i As Integer
		///           For i = 1 To itemnames.Length - 1
		///               ' will add Files or Dirs, recursing and flattening subdirectories.
		///               zip.AddItem(itemnames(i), "flat")
		///           Next i
		///           zip.Save(ZipToCreate)
		///       End Using
		///   Catch ex1 As Exception
		///       Console.Error.WriteLine("exception: {0}", ex1.ToString())
		///   End Try
		/// </code>
		/// </example>
		/// <returns>The <c>ZipEntry</c> added.</returns>
		public ZipEntry AddItem(String fileOrDirectoryName, String directoryPathInArchive)
		{
			if (File.Exists(fileOrDirectoryName))
				return AddFile(fileOrDirectoryName, directoryPathInArchive);

			if (Directory.Exists(fileOrDirectoryName))
				return AddDirectory(fileOrDirectoryName, directoryPathInArchive);

			throw new FileNotFoundException(String.Format("That file or directory ({0}) does not exist!",
														  fileOrDirectoryName));
		}

		/// <summary>
		///   Adds a File to a Zip file archive.
		/// </summary>
		/// <remarks>
		///
		/// <para>
		///   This call collects metadata for the named file in the filesystem,
		///   including the file attributes and the timestamp, and inserts that metadata
		///   into the resulting ZipEntry.  Only when the application calls Save() on
		///   the <c>ZipFile</c>, does DotNetZip read the file from the filesystem and
		///   then write the content to the zip file archive.
		/// </para>
		///
		/// <para>
		///   This method will throw an exception if an entry with the same name already
		///   exists in the <c>ZipFile</c>.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		/// <para>
		///   In this example, three files are added to a Zip archive. The ReadMe.txt
		///   file will be placed in the root of the archive. The .png file will be
		///   placed in a folder within the zip called photos\personal.  The pdf file
		///   will be included into a folder within the zip called Desktop.
		/// </para>
		/// <code>
		///    try
		///    {
		///      using (ZipFile zip = new ZipFile())
		///      {
		///        zip.AddFile("c:\\photos\\personal\\7440-N49th.png");
		///        zip.AddFile("c:\\Desktop\\2008-Regional-Sales-Report.pdf");
		///        zip.AddFile("ReadMe.txt");
		///
		///        zip.Save("Package.zip");
		///      }
		///    }
		///    catch (System.Exception ex1)
		///    {
		///      System.Console.Error.WriteLine("exception: " + ex1);
		///    }
		/// </code>
		///
		/// <code lang="VB">
		///  Try
		///       Using zip As ZipFile = New ZipFile
		///           zip.AddFile("c:\photos\personal\7440-N49th.png")
		///           zip.AddFile("c:\Desktop\2008-Regional-Sales-Report.pdf")
		///           zip.AddFile("ReadMe.txt")
		///           zip.Save("Package.zip")
		///       End Using
		///   Catch ex1 As Exception
		///       Console.Error.WriteLine("exception: {0}", ex1.ToString)
		///   End Try
		/// </code>
		/// </example>
		///
		/// <overloads>This method has two overloads.</overloads>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddItem(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.AddDirectory(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateFile(string)"/>
		///
		/// <param name="fileName">
		///   The name of the file to add. It should refer to a file in the filesystem.
		///   The name of the file may be a relative path or a fully-qualified path.
		/// </param>
		/// <returns>The <c>ZipEntry</c> corresponding to the File added.</returns>
		public ZipEntry AddFile(string fileName)
		{
			return AddFile(fileName, null);
		}





		/// <summary>
		///   Adds a File to a Zip file archive, potentially overriding the path to be
		///   used within the zip archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   The file added by this call to the <c>ZipFile</c> is not written to the
		///   zip file archive until the application calls Save() on the <c>ZipFile</c>.
		/// </para>
		///
		/// <para>
		///   This method will throw an exception if an entry with the same name already
		///   exists in the <c>ZipFile</c>.
		/// </para>
		///
		/// <para>
		///   This version of the method allows the caller to explicitly specify the
		///   directory path to be used in the archive.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		/// <para>
		///   In this example, three files are added to a Zip archive. The ReadMe.txt
		///   file will be placed in the root of the archive. The .png file will be
		///   placed in a folder within the zip called images.  The pdf file will be
		///   included into a folder within the zip called files\docs, and will be
		///   encrypted with the given password.
		/// </para>
		/// <code>
		/// try
		/// {
		///   using (ZipFile zip = new ZipFile())
		///   {
		///     // the following entry will be inserted at the root in the archive.
		///     zip.AddFile("c:\\datafiles\\ReadMe.txt", "");
		///     // this image file will be inserted into the "images" directory in the archive.
		///     zip.AddFile("c:\\photos\\personal\\7440-N49th.png", "images");
		///     // the following will result in a password-protected file called
		///     // files\\docs\\2008-Regional-Sales-Report.pdf  in the archive.
		///     zip.Password = "EncryptMe!";
		///     zip.AddFile("c:\\Desktop\\2008-Regional-Sales-Report.pdf", "files\\docs");
		///     zip.Save("Archive.zip");
		///   }
		/// }
		/// catch (System.Exception ex1)
		/// {
		///   System.Console.Error.WriteLine("exception: {0}", ex1);
		/// }
		/// </code>
		///
		/// <code lang="VB">
		///   Try
		///       Using zip As ZipFile = New ZipFile
		///           ' the following entry will be inserted at the root in the archive.
		///           zip.AddFile("c:\datafiles\ReadMe.txt", "")
		///           ' this image file will be inserted into the "images" directory in the archive.
		///           zip.AddFile("c:\photos\personal\7440-N49th.png", "images")
		///           ' the following will result in a password-protected file called
		///           ' files\\docs\\2008-Regional-Sales-Report.pdf  in the archive.
		///           zip.Password = "EncryptMe!"
		///           zip.AddFile("c:\Desktop\2008-Regional-Sales-Report.pdf", "files\documents")
		///           zip.Save("Archive.zip")
		///       End Using
		///   Catch ex1 As Exception
		///       Console.Error.WriteLine("exception: {0}", ex1)
		///   End Try
		/// </code>
		/// </example>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddItem(string,string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.AddDirectory(string, string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateFile(string,string)"/>
		///
		/// <param name="fileName">
		///   The name of the file to add.  The name of the file may be a relative path
		///   or a fully-qualified path.
		/// </param>
		///
		/// <param name="directoryPathInArchive">
		///   Specifies a directory path to use to override any path in the fileName.
		///   This path may, or may not, correspond to a real directory in the current
		///   filesystem.  If the files within the zip are later extracted, this is the
		///   path used for the extracted file.  Passing <c>null</c> (<c>Nothing</c> in
		///   VB) will use the path on the fileName, if any.  Passing the empty string
		///   ("") will insert the item at the root path within the archive.
		/// </param>
		///
		/// <returns>The <c>ZipEntry</c> corresponding to the file added.</returns>
		public ZipEntry AddFile(string fileName, String directoryPathInArchive)
		{
			string nameInArchive = ZipEntry.NameInArchive(fileName, directoryPathInArchive);
			ZipEntry ze = ZipEntry.CreateFromFile(fileName, nameInArchive);
			if (Verbose) StatusMessageTextWriter.WriteLine("adding {0}...", fileName);
			return _InternalAddEntry(ze);
		}


		/// <summary>
		///   This method removes a collection of entries from the <c>ZipFile</c>.
		/// </summary>
		///
		/// <param name="entriesToRemove">
		///   A collection of ZipEntry instances from this zip file to be removed. For
		///   example, you can pass in an array of ZipEntry instances; or you can call
		///   SelectEntries(), and then add or remove entries from that
		///   ICollection&lt;ZipEntry&gt; (ICollection(Of ZipEntry) in VB), and pass
		///   that ICollection to this method.
		/// </param>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.SelectEntries(String)" />
		/// <seealso cref="PickGold.Zip.ZipFile.RemoveSelectedEntries(String)" />
		public void RemoveEntries(System.Collections.Generic.ICollection<ZipEntry> entriesToRemove)
		{
			if (entriesToRemove == null)
				throw new ArgumentNullException("entriesToRemove");

			foreach (ZipEntry e in entriesToRemove)
			{
				this.RemoveEntry(e);
			}
		}


		/// <summary>
		///   This method removes a collection of entries from the <c>ZipFile</c>, by name.
		/// </summary>
		///
		/// <param name="entriesToRemove">
		///   A collection of strings that refer to names of entries to be removed
		///   from the <c>ZipFile</c>.  For example, you can pass in an array or a
		///   List of Strings that provide the names of entries to be removed.
		/// </param>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.SelectEntries(String)" />
		/// <seealso cref="PickGold.Zip.ZipFile.RemoveSelectedEntries(String)" />
		public void RemoveEntries(System.Collections.Generic.ICollection<String> entriesToRemove)
		{
			if (entriesToRemove == null)
				throw new ArgumentNullException("entriesToRemove");

			foreach (String e in entriesToRemove)
			{
				this.RemoveEntry(e);
			}
		}


		/// <summary>
		///   This method adds a set of files to the <c>ZipFile</c>.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   Use this method to add a set of files to the zip archive, in one call.
		///   For example, a list of files received from
		///   <c>System.IO.Directory.GetFiles()</c> can be added to a zip archive in one
		///   call.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to each
		///   ZipEntry added.
		/// </para>
		/// </remarks>
		///
		/// <param name="fileNames">
		///   The collection of names of the files to add. Each string should refer to a
		///   file in the filesystem. The name of the file may be a relative path or a
		///   fully-qualified path.
		/// </param>
		///
		/// <example>
		///   This example shows how to create a zip file, and add a few files into it.
		/// <code>
		/// String ZipFileToCreate = "archive1.zip";
		/// String DirectoryToZip = "c:\\reports";
		/// using (ZipFile zip = new ZipFile())
		/// {
		///   // Store all files found in the top level directory, into the zip archive.
		///   String[] filenames = System.IO.Directory.GetFiles(DirectoryToZip);
		///   zip.AddFiles(filenames);
		///   zip.Save(ZipFileToCreate);
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Dim ZipFileToCreate As String = "archive1.zip"
		/// Dim DirectoryToZip As String = "c:\reports"
		/// Using zip As ZipFile = New ZipFile
		///     ' Store all files found in the top level directory, into the zip archive.
		///     Dim filenames As String() = System.IO.Directory.GetFiles(DirectoryToZip)
		///     zip.AddFiles(filenames)
		///     zip.Save(ZipFileToCreate)
		/// End Using
		/// </code>
		/// </example>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddSelectedFiles(String, String)" />
		public void AddFiles(System.Collections.Generic.IEnumerable<String> fileNames)
		{
			this.AddFiles(fileNames, null);
		}


		/// <summary>
		///   Adds or updates a set of files in the <c>ZipFile</c>.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   Any files that already exist in the archive are updated. Any files that
		///   don't yet exist in the archive are added.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to each
		///   ZipEntry added.
		/// </para>
		/// </remarks>
		///
		/// <param name="fileNames">
		///   The collection of names of the files to update. Each string should refer to a file in
		///   the filesystem. The name of the file may be a relative path or a fully-qualified path.
		/// </param>
		///
		public void UpdateFiles(System.Collections.Generic.IEnumerable<String> fileNames)
		{
			this.UpdateFiles(fileNames, null);
		}


		/// <summary>
		///   Adds a set of files to the <c>ZipFile</c>, using the
		///   specified directory path in the archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   Any directory structure that may be present in the
		///   filenames contained in the list is "flattened" in the
		///   archive.  Each file in the list is added to the archive in
		///   the specified top-level directory.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see
		///   cref="Encryption"/>, <see cref="Password"/>, <see
		///   cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see
		///   cref="ExtractExistingFile"/>, <see
		///   cref="ZipErrorAction"/>, and <see
		///   cref="CompressionLevel"/>, their respective values at the
		///   time of this call will be applied to each ZipEntry added.
		/// </para>
		/// </remarks>
		///
		/// <param name="fileNames">
		///   The names of the files to add. Each string should refer to
		///   a file in the filesystem.  The name of the file may be a
		///   relative path or a fully-qualified path.
		/// </param>
		///
		/// <param name="directoryPathInArchive">
		///   Specifies a directory path to use to override any path in the file name.
		///   Th is path may, or may not, correspond to a real directory in the current
		///   filesystem.  If the files within the zip are later extracted, this is the
		///   path used for the extracted file.  Passing <c>null</c> (<c>Nothing</c> in
		///   VB) will use the path on each of the <c>fileNames</c>, if any.  Passing
		///   the empty string ("") will insert the item at the root path within the
		///   archive.
		/// </param>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddSelectedFiles(String, String)" />
		public void AddFiles(System.Collections.Generic.IEnumerable<String> fileNames, String directoryPathInArchive)
		{
			AddFiles(fileNames, false, directoryPathInArchive);
		}



		/// <summary>
		///   Adds a set of files to the <c>ZipFile</c>, using the specified directory
		///   path in the archive, and preserving the full directory structure in the
		///   filenames.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   Think of the <paramref name="directoryPathInArchive"/> as a "root" or
		///   base directory used in the archive for the files that get added.  when
		///   <paramref name="preserveDirHierarchy"/> is true, the hierarchy of files
		///   found in the filesystem will be placed, with the hierarchy intact,
		///   starting at that root in the archive. When <c>preserveDirHierarchy</c>
		///   is false, the path hierarchy of files is flattned, and the flattened
		///   set of files gets placed in the root within the archive as specified in
		///   <c>directoryPathInArchive</c>.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to each
		///   ZipEntry added.
		/// </para>
		///
		/// </remarks>
		///
		/// <param name="fileNames">
		///   The names of the files to add. Each string should refer to a file in the
		///   filesystem.  The name of the file may be a relative path or a
		///   fully-qualified path.
		/// </param>
		///
		/// <param name="directoryPathInArchive">
		///   Specifies a directory path to use as a prefix for each entry name.
		///   This path may, or may not, correspond to a real directory in the current
		///   filesystem.  If the files within the zip are later extracted, this is the
		///   path used for the extracted file.  Passing <c>null</c> (<c>Nothing</c> in
		///   VB) will use the path on each of the <c>fileNames</c>, if any.  Passing
		///   the empty string ("") will insert the item at the root path within the
		///   archive.
		/// </param>
		///
		/// <param name="preserveDirHierarchy">
		///   whether the entries in the zip archive will reflect the directory
		///   hierarchy that is present in the various filenames.  For example, if
		///   <paramref name="fileNames"/> includes two paths,
		///   \Animalia\Chordata\Mammalia\Info.txt and
		///   \Plantae\Magnoliophyta\Dicotyledon\Info.txt, then calling this method
		///   with <paramref name="preserveDirHierarchy"/> = <c>false</c> will
		///   result in an exception because of a duplicate entry name, while
		///   calling this method with <paramref name="preserveDirHierarchy"/> =
		///   <c>true</c> will result in the full direcory paths being included in
		///   the entries added to the ZipFile.
		/// </param>
		/// <seealso cref="PickGold.Zip.ZipFile.AddSelectedFiles(String, String)" />
		public void AddFiles(System.Collections.Generic.IEnumerable<String> fileNames,
							 bool preserveDirHierarchy,
							 String directoryPathInArchive)
		{
			if (fileNames == null)
				throw new ArgumentNullException("fileNames");

			_addOperationCanceled = false;
			OnAddStarted();
			if (preserveDirHierarchy)
			{
				foreach (var f in fileNames)
				{
					if (_addOperationCanceled) break;
					if (directoryPathInArchive != null)
					{
						//string s = SharedUtilities.NormalizePath(Path.Combine(directoryPathInArchive, Path.GetDirectoryName(f)));
						string s = Path.GetFullPath(Path.Combine(directoryPathInArchive, Path.GetDirectoryName(f)));
						this.AddFile(f, s);
					}
					else
						this.AddFile(f, null);
				}
			}
			else
			{
				foreach (var f in fileNames)
				{
					if (_addOperationCanceled) break;
					this.AddFile(f, directoryPathInArchive);
				}
			}
			if (!_addOperationCanceled)
				OnAddCompleted();
		}


		/// <summary>
		///   Adds or updates a set of files to the <c>ZipFile</c>, using the specified
		///   directory path in the archive.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   Any files that already exist in the archive are updated. Any files that
		///   don't yet exist in the archive are added.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to each
		///   ZipEntry added.
		/// </para>
		/// </remarks>
		///
		/// <param name="fileNames">
		///   The names of the files to add or update. Each string should refer to a
		///   file in the filesystem.  The name of the file may be a relative path or a
		///   fully-qualified path.
		/// </param>
		///
		/// <param name="directoryPathInArchive">
		///   Specifies a directory path to use to override any path in the file name.
		///   This path may, or may not, correspond to a real directory in the current
		///   filesystem.  If the files within the zip are later extracted, this is the
		///   path used for the extracted file.  Passing <c>null</c> (<c>Nothing</c> in
		///   VB) will use the path on each of the <c>fileNames</c>, if any.  Passing
		///   the empty string ("") will insert the item at the root path within the
		///   archive.
		/// </param>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddSelectedFiles(String, String)" />
		public void UpdateFiles(System.Collections.Generic.IEnumerable<String> fileNames, String directoryPathInArchive)
		{
			if (fileNames == null)
				throw new ArgumentNullException("fileNames");

			OnAddStarted();
			foreach (var f in fileNames)
				this.UpdateFile(f, directoryPathInArchive);
			OnAddCompleted();
		}




		/// <summary>
		///   Adds or Updates a File in a Zip file archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This method adds a file to a zip archive, or, if the file already exists
		///   in the zip archive, this method Updates the content of that given filename
		///   in the zip archive.  The <c>UpdateFile</c> method might more accurately be
		///   called "AddOrUpdateFile".
		/// </para>
		///
		/// <para>
		///   Upon success, there is no way for the application to learn whether the file
		///   was added versus updated.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		/// </remarks>
		///
		/// <example>
		///
		///   This example shows how to Update an existing entry in a zipfile. The first
		///   call to UpdateFile adds the file to the newly-created zip archive.  The
		///   second call to UpdateFile updates the content for that file in the zip
		///   archive.
		///
		/// <code>
		/// using (ZipFile zip1 = new ZipFile())
		/// {
		///   // UpdateFile might more accurately be called "AddOrUpdateFile"
		///   zip1.UpdateFile("MyDocuments\\Readme.txt");
		///   zip1.UpdateFile("CustomerList.csv");
		///   zip1.Comment = "This zip archive has been created.";
		///   zip1.Save("Content.zip");
		/// }
		///
		/// using (ZipFile zip2 = ZipFile.Read("Content.zip"))
		/// {
		///   zip2.UpdateFile("Updates\\Readme.txt");
		///   zip2.Comment = "This zip archive has been updated: The Readme.txt file has been changed.";
		///   zip2.Save();
		/// }
		///
		/// </code>
		/// <code lang="VB">
		///   Using zip1 As New ZipFile
		///       ' UpdateFile might more accurately be called "AddOrUpdateFile"
		///       zip1.UpdateFile("MyDocuments\Readme.txt")
		///       zip1.UpdateFile("CustomerList.csv")
		///       zip1.Comment = "This zip archive has been created."
		///       zip1.Save("Content.zip")
		///   End Using
		///
		///   Using zip2 As ZipFile = ZipFile.Read("Content.zip")
		///       zip2.UpdateFile("Updates\Readme.txt")
		///       zip2.Comment = "This zip archive has been updated: The Readme.txt file has been changed."
		///       zip2.Save
		///   End Using
		/// </code>
		/// </example>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddFile(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateDirectory(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateItem(string)"/>
		///
		/// <param name="fileName">
		///   The name of the file to add or update. It should refer to a file in the
		///   filesystem.  The name of the file may be a relative path or a
		///   fully-qualified path.
		/// </param>
		///
		/// <returns>
		///   The <c>ZipEntry</c> corresponding to the File that was added or updated.
		/// </returns>
		public ZipEntry UpdateFile(string fileName)
		{
			return UpdateFile(fileName, null);
		}



		/// <summary>
		///   Adds or Updates a File in a Zip file archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This method adds a file to a zip archive, or, if the file already exists
		///   in the zip archive, this method Updates the content of that given filename
		///   in the zip archive.
		/// </para>
		///
		/// <para>
		///   This version of the method allows the caller to explicitly specify the
		///   directory path to be used in the archive.  The entry to be added or
		///   updated is found by using the specified directory path, combined with the
		///   basename of the specified filename.
		/// </para>
		///
		/// <para>
		///   Upon success, there is no way for the application to learn if the file was
		///   added versus updated.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		/// </remarks>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddFile(string,string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateDirectory(string,string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateItem(string,string)"/>
		///
		/// <param name="fileName">
		///   The name of the file to add or update. It should refer to a file in the
		///   filesystem.  The name of the file may be a relative path or a
		///   fully-qualified path.
		/// </param>
		///
		/// <param name="directoryPathInArchive">
		///   Specifies a directory path to use to override any path in the
		///   <c>fileName</c>.  This path may, or may not, correspond to a real
		///   directory in the current filesystem.  If the files within the zip are
		///   later extracted, this is the path used for the extracted file.  Passing
		///   <c>null</c> (<c>Nothing</c> in VB) will use the path on the
		///   <c>fileName</c>, if any.  Passing the empty string ("") will insert the
		///   item at the root path within the archive.
		/// </param>
		///
		/// <returns>
		///   The <c>ZipEntry</c> corresponding to the File that was added or updated.
		/// </returns>
		public ZipEntry UpdateFile(string fileName, String directoryPathInArchive)
		{
			// ideally this would all be transactional!
			var key = ZipEntry.NameInArchive(fileName, directoryPathInArchive);
			if (this[key] != null)
				this.RemoveEntry(key);
			return this.AddFile(fileName, directoryPathInArchive);
		}





		/// <summary>
		///   Add or update a directory in a zip archive.
		/// </summary>
		///
		/// <remarks>
		///   If the specified directory does not exist in the archive, then this method
		///   is equivalent to calling <c>AddDirectory()</c>.  If the specified
		///   directory already exists in the archive, then this method updates any
		///   existing entries, and adds any new entries. Any entries that are in the
		///   zip archive but not in the specified directory, are left alone.  In other
		///   words, the contents of the zip file will be a union of the previous
		///   contents and the new files.
		/// </remarks>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateFile(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.AddDirectory(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateItem(string)"/>
		///
		/// <param name="directoryName">
		///   The path to the directory to be added to the zip archive, or updated in
		///   the zip archive.
		/// </param>
		///
		/// <returns>
		/// The <c>ZipEntry</c> corresponding to the Directory that was added or updated.
		/// </returns>
		public ZipEntry UpdateDirectory(string directoryName)
		{
			return UpdateDirectory(directoryName, null);
		}


		/// <summary>
		///   Add or update a directory in the zip archive at the specified root
		///   directory in the archive.
		/// </summary>
		///
		/// <remarks>
		///   If the specified directory does not exist in the archive, then this method
		///   is equivalent to calling <c>AddDirectory()</c>.  If the specified
		///   directory already exists in the archive, then this method updates any
		///   existing entries, and adds any new entries. Any entries that are in the
		///   zip archive but not in the specified directory, are left alone.  In other
		///   words, the contents of the zip file will be a union of the previous
		///   contents and the new files.
		/// </remarks>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateFile(string,string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.AddDirectory(string,string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateItem(string,string)"/>
		///
		/// <param name="directoryName">
		///   The path to the directory to be added to the zip archive, or updated
		///   in the zip archive.
		/// </param>
		///
		/// <param name="directoryPathInArchive">
		///   Specifies a directory path to use to override any path in the
		///   <c>directoryName</c>.  This path may, or may not, correspond to a real
		///   directory in the current filesystem.  If the files within the zip are
		///   later extracted, this is the path used for the extracted file.  Passing
		///   <c>null</c> (<c>Nothing</c> in VB) will use the path on the
		///   <c>directoryName</c>, if any.  Passing the empty string ("") will insert
		///   the item at the root path within the archive.
		/// </param>
		///
		/// <returns>
		///   The <c>ZipEntry</c> corresponding to the Directory that was added or updated.
		/// </returns>
		public ZipEntry UpdateDirectory(string directoryName, String directoryPathInArchive)
		{
			return this.AddOrUpdateDirectoryImpl(directoryName, directoryPathInArchive, AddOrUpdateAction.AddOrUpdate);
		}





		/// <summary>
		///   Add or update a file or directory in the zip archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This is useful when the application is not sure or does not care if the
		///   item to be added is a file or directory, and does not know or does not
		///   care if the item already exists in the <c>ZipFile</c>. Calling this method
		///   is equivalent to calling <c>RemoveEntry()</c> if an entry by the same name
		///   already exists, followed calling by <c>AddItem()</c>.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		/// </remarks>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddItem(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateFile(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateDirectory(string)"/>
		///
		/// <param name="itemName">
		///  the path to the file or directory to be added or updated.
		/// </param>
		public void UpdateItem(string itemName)
		{
			UpdateItem(itemName, null);
		}


		/// <summary>
		///   Add or update a file or directory.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This method is useful when the application is not sure or does not care if
		///   the item to be added is a file or directory, and does not know or does not
		///   care if the item already exists in the <c>ZipFile</c>. Calling this method
		///   is equivalent to calling <c>RemoveEntry()</c>, if an entry by that name
		///   exists, and then calling <c>AddItem()</c>.
		/// </para>
		///
		/// <para>
		///   This version of the method allows the caller to explicitly specify the
		///   directory path to be used for the item being added to the archive.  The
		///   entry or entries that are added or updated will use the specified
		///   <c>DirectoryPathInArchive</c>. Extracting the entry from the archive will
		///   result in a file stored in that directory path.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		/// </remarks>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddItem(string, string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateFile(string, string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateDirectory(string, string)"/>
		///
		/// <param name="itemName">
		///   The path for the File or Directory to be added or updated.
		/// </param>
		/// <param name="directoryPathInArchive">
		///   Specifies a directory path to use to override any path in the
		///   <c>itemName</c>.  This path may, or may not, correspond to a real
		///   directory in the current filesystem.  If the files within the zip are
		///   later extracted, this is the path used for the extracted file.  Passing
		///   <c>null</c> (<c>Nothing</c> in VB) will use the path on the
		///   <c>itemName</c>, if any.  Passing the empty string ("") will insert the
		///   item at the root path within the archive.
		/// </param>
		public void UpdateItem(string itemName, string directoryPathInArchive)
		{
			if (File.Exists(itemName))
				UpdateFile(itemName, directoryPathInArchive);

			else if (Directory.Exists(itemName))
				UpdateDirectory(itemName, directoryPathInArchive);

			else
				throw new FileNotFoundException(String.Format("That file or directory ({0}) does not exist!", itemName));
		}




		/// <summary>
		///   Adds a named entry into the zip archive, taking content for the entry
		///   from a string.
		/// </summary>
		///
		/// <remarks>
		///   Calling this method creates an entry using the given fileName and
		///   directory path within the archive.  There is no need for a file by the
		///   given name to exist in the filesystem; the name is used within the zip
		///   archive only. The content for the entry is encoded using the default text
		///   encoding for the machine, or on Silverlight, using UTF-8.
		/// </remarks>
		///
		/// <param name="content">
		///   The content of the file, should it be extracted from the zip.
		/// </param>
		///
		/// <param name="entryName">
		///   The name, including any path, to use for the entry within the archive.
		/// </param>
		///
		/// <returns>The <c>ZipEntry</c> added.</returns>
		///
		/// <example>
		///
		/// This example shows how to add an entry to the zipfile, using a string as
		/// content for that entry.
		///
		/// <code lang="C#">
		/// string Content = "This string will be the content of the Readme.txt file in the zip archive.";
		/// using (ZipFile zip1 = new ZipFile())
		/// {
		///   zip1.AddFile("MyDocuments\\Resume.doc", "files");
		///   zip1.AddEntry("Readme.txt", Content);
		///   zip1.Comment = "This zip file was created at " + System.DateTime.Now.ToString("G");
		///   zip1.Save("Content.zip");
		/// }
		///
		/// </code>
		/// <code lang="VB">
		/// Public Sub Run()
		///   Dim Content As String = "This string will be the content of the Readme.txt file in the zip archive."
		///   Using zip1 As ZipFile = New ZipFile
		///     zip1.AddEntry("Readme.txt", Content)
		///     zip1.AddFile("MyDocuments\Resume.doc", "files")
		///     zip1.Comment = ("This zip file was created at " &amp; DateTime.Now.ToString("G"))
		///     zip1.Save("Content.zip")
		///   End Using
		/// End Sub
		/// </code>
		/// </example>
		public ZipEntry AddEntry(string entryName, string content)
		{
#if SILVERLIGHT
            return AddEntry(entryName, content, System.Text.Encoding.UTF8);
#else
			return AddEntry(entryName, content, System.Text.Encoding.Default);
#endif
		}



		/// <summary>
		///   Adds a named entry into the zip archive, taking content for the entry
		///   from a string, and using the specified text encoding.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   Calling this method creates an entry using the given fileName and
		///   directory path within the archive.  There is no need for a file by the
		///   given name to exist in the filesystem; the name is used within the zip
		///   archive only.
		/// </para>
		///
		/// <para>
		///   The content for the entry, a string value, is encoded using the given
		///   text encoding. A BOM (byte-order-mark) is emitted into the file, if the
		///   Encoding parameter is set for that.
		/// </para>
		///
		/// <para>
		///   Most Encoding classes support a constructor that accepts a boolean,
		///   indicating whether to emit a BOM or not. For example see <see
		///   cref="System.Text.UTF8Encoding(bool)"/>.
		/// </para>
		///
		/// </remarks>
		///
		/// <param name="entryName">
		///   The name, including any path, to use within the archive for the entry.
		/// </param>
		///
		/// <param name="content">
		///   The content of the file, should it be extracted from the zip.
		/// </param>
		///
		/// <param name="encoding">
		///   The text encoding to use when encoding the string. Be aware: This is
		///   distinct from the text encoding used to encode the fileName, as specified
		///   in <see cref="ProvisionalAlternateEncoding" />.
		/// </param>
		///
		/// <returns>The <c>ZipEntry</c> added.</returns>
		///
		public ZipEntry AddEntry(string entryName, string content, System.Text.Encoding encoding)
		{
			// cannot employ a using clause here.  We need the stream to
			// persist after exit from this method.
			var ms = new MemoryStream();

			// cannot use a using clause here; StreamWriter takes
			// ownership of the stream and Disposes it before we are ready.
			var sw = new StreamWriter(ms, encoding);
			sw.Write(content);
			sw.Flush();

			// reset to allow reading later
			ms.Seek(0, SeekOrigin.Begin);

			return AddEntry(entryName, ms);

			// must not dispose the MemoryStream - it will be used later.
		}


		/// <summary>
		///   Create an entry in the <c>ZipFile</c> using the given <c>Stream</c>
		///   as input.  The entry will have the given filename.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   The application should provide an open, readable stream; in this case it
		///   will be read during the call to <see cref="ZipFile.Save()"/> or one of
		///   its overloads.
		/// </para>
		///
		/// <para>
		///   The passed stream will be read from its current position. If
		///   necessary, callers should set the position in the stream before
		///   calling AddEntry(). This might be appropriate when using this method
		///   with a MemoryStream, for example.
		/// </para>
		///
		/// <para>
		///   In cases where a large number of streams will be added to the
		///   <c>ZipFile</c>, the application may wish to avoid maintaining all of the
		///   streams open simultaneously.  To handle this situation, the application
		///   should use the <see cref="AddEntry(string, OpenDelegate, CloseDelegate)"/>
		///   overload.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		/// <para>
		///   This example adds a single entry to a <c>ZipFile</c> via a <c>Stream</c>.
		/// </para>
		///
		/// <code lang="C#">
		/// String zipToCreate = "Content.zip";
		/// String fileNameInArchive = "Content-From-Stream.bin";
		/// using (System.IO.Stream streamToRead = MyStreamOpener())
		/// {
		///   using (ZipFile zip = new ZipFile())
		///   {
		///     ZipEntry entry= zip.AddEntry(fileNameInArchive, streamToRead);
		///     zip.AddFile("Readme.txt");
		///     zip.Save(zipToCreate);  // the stream is read implicitly here
		///   }
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Dim zipToCreate As String = "Content.zip"
		/// Dim fileNameInArchive As String = "Content-From-Stream.bin"
		/// Using streamToRead as System.IO.Stream = MyStreamOpener()
		///   Using zip As ZipFile = New ZipFile()
		///     Dim entry as ZipEntry = zip.AddEntry(fileNameInArchive, streamToRead)
		///     zip.AddFile("Readme.txt")
		///     zip.Save(zipToCreate)  '' the stream is read implicitly, here
		///   End Using
		/// End Using
		/// </code>
		/// </example>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateEntry(string, System.IO.Stream)"/>
		///
		/// <param name="entryName">
		///   The name, including any path, which is shown in the zip file for the added
		///   entry.
		/// </param>
		/// <param name="stream">
		///   The input stream from which to grab content for the file
		/// </param>
		/// <returns>The <c>ZipEntry</c> added.</returns>
		public ZipEntry AddEntry(string entryName, Stream stream)
		{
			ZipEntry ze = ZipEntry.CreateForStream(entryName, stream);
			ze.SetEntryTimes(DateTime.Now, DateTime.Now, DateTime.Now);
			if (Verbose) StatusMessageTextWriter.WriteLine("adding {0}...", entryName);
			return _InternalAddEntry(ze);
		}



		/// <summary>
		///   Add a ZipEntry for which content is written directly by the application.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   When the application needs to write the zip entry data, use this
		///   method to add the ZipEntry. For example, in the case that the
		///   application wishes to write the XML representation of a DataSet into
		///   a ZipEntry, the application can use this method to do so.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		///
		/// <para>
		///   About progress events: When using the WriteDelegate, DotNetZip does
		///   not issue any SaveProgress events with <c>EventType</c> = <see
		///   cref="ZipProgressEventType.Saving_EntryBytesRead">
		///   Saving_EntryBytesRead</see>. (This is because it is the
		///   application's code that runs in WriteDelegate - there's no way for
		///   DotNetZip to know when to issue a EntryBytesRead event.)
		///   Applications that want to update a progress bar or similar status
		///   indicator should do so from within the WriteDelegate
		///   itself. DotNetZip will issue the other SaveProgress events,
		///   including <see cref="ZipProgressEventType.Saving_Started">
		///   Saving_Started</see>,
		///   <see cref="ZipProgressEventType.Saving_BeforeWriteEntry">
		///   Saving_BeforeWriteEntry</see>, and <see
		///   cref="ZipProgressEventType.Saving_AfterWriteEntry">
		///   Saving_AfterWriteEntry</see>.
		/// </para>
		///
		/// <para>
		///   Note: When you use PKZip encryption, it's normally necessary to
		///   compute the CRC of the content to be encrypted, before compressing or
		///   encrypting it. Therefore, when using PKZip encryption with a
		///   WriteDelegate, the WriteDelegate CAN BE called twice: once to compute
		///   the CRC, and the second time to potentially compress and
		///   encrypt. Surprising, but true. This is because PKWARE specified that
		///   the encryption initialization data depends on the CRC.
		///   If this happens, for each call of the delegate, your
		///   application must stream the same entry data in its entirety. If your
		///   application writes different data during the second call, it will
		///   result in a corrupt zip file.
		/// </para>
		///
		/// <para>
		///   The double-read behavior happens with all types of entries, not only
		///   those that use WriteDelegate. It happens if you add an entry from a
		///   filesystem file, or using a string, or a stream, or an opener/closer
		///   pair. But in those cases, DotNetZip takes care of reading twice; in
		///   the case of the WriteDelegate, the application code gets invoked
		///   twice. Be aware.
		/// </para>
		///
		/// <para>
		///   As you can imagine, this can cause performance problems for large
		///   streams, and it can lead to correctness problems when you use a
		///   <c>WriteDelegate</c>. This is a pretty big pitfall.  There are two
		///   ways to avoid it.  First, and most preferred: don't use PKZIP
		///   encryption.  If you use the WinZip AES encryption, this problem
		///   doesn't occur, because the encryption protocol doesn't require the CRC
		///   up front. Second: if you do choose to use PKZIP encryption, write out
		///   to a non-seekable stream (like standard output, or the
		///   Response.OutputStream in an ASP.NET application).  In this case,
		///   DotNetZip will use an alternative encryption protocol that does not
		///   rely on the CRC of the content.  This also implies setting bit 3 in
		///   the zip entry, which still presents problems for some zip tools.
		/// </para>
		///
		/// <para>
		///   In the future I may modify DotNetZip to *always* use bit 3 when PKZIP
		///   encryption is in use.  This seems like a win overall, but there will
		///   be some work involved.  If you feel strongly about it, visit the
		///   DotNetZip forums and vote up <see
		///   href="http://dotnetzip.codeplex.com/workitem/13686">the Workitem
		///   tracking this issue</see>.
		/// </para>
		///
		/// </remarks>
		///
		/// <param name="entryName">the name of the entry to add</param>
		/// <param name="writer">the delegate which will write the entry content</param>
		/// <returns>the ZipEntry added</returns>
		///
		/// <example>
		///
		///   This example shows an application filling a DataSet, then saving the
		///   contents of that DataSet as XML, into a ZipEntry in a ZipFile, using an
		///   anonymous delegate in C#. The DataSet XML is never saved to a disk file.
		///
		/// <code lang="C#">
		/// var c1= new System.Data.SqlClient.SqlConnection(connstring1);
		/// var da = new System.Data.SqlClient.SqlDataAdapter()
		///     {
		///         SelectCommand=  new System.Data.SqlClient.SqlCommand(strSelect, c1)
		///     };
		///
		/// DataSet ds1 = new DataSet();
		/// da.Fill(ds1, "Invoices");
		///
		/// using(PickGold.Zip.ZipFile zip = new PickGold.Zip.ZipFile())
		/// {
		///     zip.AddEntry(zipEntryName, (name,stream) => ds1.WriteXml(stream) );
		///     zip.Save(zipFileName);
		/// }
		/// </code>
		/// </example>
		///
		/// <example>
		///
		/// This example uses an anonymous method in C# as the WriteDelegate to provide
		/// the data for the ZipEntry. The example is a bit contrived - the
		/// <c>AddFile()</c> method is a simpler way to insert the contents of a file
		/// into an entry in a zip file. On the other hand, if there is some sort of
		/// processing or transformation of the file contents required before writing,
		/// the application could use the <c>WriteDelegate</c> to do it, in this way.
		///
		/// <code lang="C#">
		/// using (var input = File.Open(filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite ))
		/// {
		///     using(PickGold.Zip.ZipFile zip = new PickGold.Zip.ZipFile())
		///     {
		///         zip.AddEntry(zipEntryName, (name,output) =>
		///             {
		///                 byte[] buffer = new byte[BufferSize];
		///                 int n;
		///                 while ((n = input.Read(buffer, 0, buffer.Length)) != 0)
		///                 {
		///                     // could transform the data here...
		///                     output.Write(buffer, 0, n);
		///                     // could update a progress bar here
		///                 }
		///             });
		///
		///         zip.Save(zipFileName);
		///     }
		/// }
		/// </code>
		/// </example>
		///
		/// <example>
		///
		/// This example uses a named delegate in VB to write data for the given
		/// ZipEntry (VB9 does not have anonymous delegates). The example here is a bit
		/// contrived - a simpler way to add the contents of a file to a ZipEntry is to
		/// simply use the appropriate <c>AddFile()</c> method.  The key scenario for
		/// which the <c>WriteDelegate</c> makes sense is saving a DataSet, in XML
		/// format, to the zip file. The DataSet can write XML to a stream, and the
		/// WriteDelegate is the perfect place to write into the zip file.  There may be
		/// other data structures that can write to a stream, but cannot be read as a
		/// stream.  The <c>WriteDelegate</c> would be appropriate for those cases as
		/// well.
		///
		/// <code lang="VB">
		/// Private Sub WriteEntry (ByVal name As String, ByVal output As Stream)
		///     Using input As FileStream = File.Open(filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)
		///         Dim n As Integer = -1
		///         Dim buffer As Byte() = New Byte(BufferSize){}
		///         Do While n &lt;&gt; 0
		///             n = input.Read(buffer, 0, buffer.Length)
		///             output.Write(buffer, 0, n)
		///         Loop
		///     End Using
		/// End Sub
		///
		/// Public Sub Run()
		///     Using zip = New ZipFile
		///         zip.AddEntry(zipEntryName, New WriteDelegate(AddressOf WriteEntry))
		///         zip.Save(zipFileName)
		///     End Using
		/// End Sub
		/// </code>
		/// </example>
		public ZipEntry AddEntry(string entryName, WriteDelegate writer)
		{
			ZipEntry ze = ZipEntry.CreateForWriter(entryName, writer);
			if (Verbose) StatusMessageTextWriter.WriteLine("adding {0}...", entryName);
			return _InternalAddEntry(ze);
		}


		/// <summary>
		///   Add an entry, for which the application will provide a stream
		///   containing the entry data, on a just-in-time basis.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   In cases where the application wishes to open the stream that
		///   holds the content for the ZipEntry, on a just-in-time basis, the
		///   application can use this method.  The application provides an
		///   opener delegate that will be called by the DotNetZip library to
		///   obtain a readable stream that can be read to get the bytes for
		///   the given entry.  Typically, this delegate opens a stream.
		///   Optionally, the application can provide a closer delegate as
		///   well, which will be called by DotNetZip when all bytes have been
		///   read from the entry.
		/// </para>
		///
		/// <para>
		///   These delegates are called from within the scope of the call to
		///   ZipFile.Save().
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		///
		///   This example uses anonymous methods in C# to open and close the
		///   source stream for the content for a zip entry.
		///
		/// <code lang="C#">
		/// using(PickGold.Zip.ZipFile zip = new PickGold.Zip.ZipFile())
		/// {
		///     zip.AddEntry(zipEntryName,
		///                  (name) =>  File.Open(filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite ),
		///                  (name, stream) =>  stream.Close()
		///                  );
		///
		///     zip.Save(zipFileName);
		/// }
		/// </code>
		///
		/// </example>
		///
		/// <example>
		///
		///   This example uses delegates in VB.NET to open and close the
		///   the source stream for the content for a zip entry.  VB 9.0 lacks
		///   support for "Sub" lambda expressions, and so the CloseDelegate must
		///   be an actual, named Sub.
		///
		/// <code lang="VB">
		///
		/// Function MyStreamOpener(ByVal entryName As String) As Stream
		///     '' This simply opens a file.  You probably want to do somethinig
		///     '' more involved here: open a stream to read from a database,
		///     '' open a stream on an HTTP connection, and so on.
		///     Return File.OpenRead(entryName)
		/// End Function
		///
		/// Sub MyStreamCloser(entryName As String, stream As Stream)
		///     stream.Close()
		/// End Sub
		///
		/// Public Sub Run()
		///     Dim dirToZip As String = "fodder"
		///     Dim zipFileToCreate As String = "Archive.zip"
		///     Dim opener As OpenDelegate = AddressOf MyStreamOpener
		///     Dim closer As CloseDelegate = AddressOf MyStreamCloser
		///     Dim numFilestoAdd As Int32 = 4
		///     Using zip As ZipFile = New ZipFile
		///         Dim i As Integer
		///         For i = 0 To numFilesToAdd - 1
		///             zip.AddEntry(String.Format("content-{0:000}.txt"), opener, closer)
		///         Next i
		///         zip.Save(zipFileToCreate)
		///     End Using
		/// End Sub
		///
		/// </code>
		/// </example>
		///
		/// <param name="entryName">the name of the entry to add</param>
		/// <param name="opener">
		///  the delegate that will be invoked by ZipFile.Save() to get the
		///  readable stream for the given entry. ZipFile.Save() will call
		///  read on this stream to obtain the data for the entry. This data
		///  will then be compressed and written to the newly created zip
		///  file.
		/// </param>
		/// <param name="closer">
		///  the delegate that will be invoked to close the stream. This may
		///  be null (Nothing in VB), in which case no call is makde to close
		///  the stream.
		/// </param>
		/// <returns>the ZipEntry added</returns>
		///
		public ZipEntry AddEntry(string entryName, OpenDelegate opener, CloseDelegate closer)
		{
			ZipEntry ze = ZipEntry.CreateForJitStreamProvider(entryName, opener, closer);
			ze.SetEntryTimes(DateTime.Now, DateTime.Now, DateTime.Now);
			if (Verbose) StatusMessageTextWriter.WriteLine("adding {0}...", entryName);
			return _InternalAddEntry(ze);
		}



		private ZipEntry _InternalAddEntry(ZipEntry ze)
		{
			// stamp all the props onto the entry
			ze._container = new ZipContainer(this);
			ze.CompressionMethod = this.CompressionMethod;
			ze.CompressionLevel = this.CompressionLevel;
			ze.ExtractExistingFile = this.ExtractExistingFile;
			ze.ZipErrorAction = this.ZipErrorAction;
			ze.SetCompression = this.SetCompression;
			ze.AlternateEncoding = this.AlternateEncoding;
			ze.AlternateEncodingUsage = this.AlternateEncodingUsage;
			ze.Password = this._Password;
			ze.Encryption = this.Encryption;
			ze.EmitTimesInWindowsFormatWhenSaving = this._emitNtfsTimes;
			ze.EmitTimesInUnixFormatWhenSaving = this._emitUnixTimes;
			//string key = DictionaryKeyForEntry(ze);
			InternalAddEntry(ze.FileName, ze);
			AfterAddEntry(ze);
			return ze;
		}




		/// <summary>
		///   Updates the given entry in the <c>ZipFile</c>, using the given
		///   string as content for the <c>ZipEntry</c>.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   Calling this method is equivalent to removing the <c>ZipEntry</c> for
		///   the given file name and directory path, if it exists, and then calling
		///   <see cref="AddEntry(String,String)" />.  See the documentation for
		///   that method for further explanation. The string content is encoded
		///   using the default encoding for the machine, or on Silverlight, using
		///   UTF-8. This encoding is distinct from the encoding used for the
		///   filename itself.  See <see cref="AlternateEncoding"/>.
		/// </para>
		///
		/// </remarks>
		///
		/// <param name="entryName">
		///   The name, including any path, to use within the archive for the entry.
		/// </param>
		///
		/// <param name="content">
		///   The content of the file, should it be extracted from the zip.
		/// </param>
		///
		/// <returns>The <c>ZipEntry</c> added.</returns>
		///
		public ZipEntry UpdateEntry(string entryName, string content)
		{
#if SILVERLIGHT
            return UpdateEntry(entryName, content, System.Text.Encoding.UTF8);
#else
			return UpdateEntry(entryName, content, System.Text.Encoding.Default);
#endif
		}


		/// <summary>
		///   Updates the given entry in the <c>ZipFile</c>, using the given string as
		///   content for the <c>ZipEntry</c>.
		/// </summary>
		///
		/// <remarks>
		///   Calling this method is equivalent to removing the <c>ZipEntry</c> for the
		///   given file name and directory path, if it exists, and then calling <see
		///   cref="AddEntry(String,String, System.Text.Encoding)" />.  See the
		///   documentation for that method for further explanation.
		/// </remarks>
		///
		/// <param name="entryName">
		///   The name, including any path, to use within the archive for the entry.
		/// </param>
		///
		/// <param name="content">
		///   The content of the file, should it be extracted from the zip.
		/// </param>
		///
		/// <param name="encoding">
		///   The text encoding to use when encoding the string. Be aware: This is
		///   distinct from the text encoding used to encode the filename. See <see
		///   cref="AlternateEncoding" />.
		/// </param>
		///
		/// <returns>The <c>ZipEntry</c> added.</returns>
		///
		public ZipEntry UpdateEntry(string entryName, string content, System.Text.Encoding encoding)
		{
			RemoveEntryForUpdate(entryName);
			return AddEntry(entryName, content, encoding);
		}



		/// <summary>
		///   Updates the given entry in the <c>ZipFile</c>, using the given delegate
		///   as the source for content for the <c>ZipEntry</c>.
		/// </summary>
		///
		/// <remarks>
		///   Calling this method is equivalent to removing the <c>ZipEntry</c> for the
		///   given file name and directory path, if it exists, and then calling <see
		///   cref="AddEntry(String,WriteDelegate)" />.  See the
		///   documentation for that method for further explanation.
		/// </remarks>
		///
		/// <param name="entryName">
		///   The name, including any path, to use within the archive for the entry.
		/// </param>
		///
		/// <param name="writer">the delegate which will write the entry content.</param>
		///
		/// <returns>The <c>ZipEntry</c> added.</returns>
		///
		public ZipEntry UpdateEntry(string entryName, WriteDelegate writer)
		{
			RemoveEntryForUpdate(entryName);
			return AddEntry(entryName, writer);
		}



		/// <summary>
		///   Updates the given entry in the <c>ZipFile</c>, using the given delegates
		///   to open and close the stream that provides the content for the <c>ZipEntry</c>.
		/// </summary>
		///
		/// <remarks>
		///   Calling this method is equivalent to removing the <c>ZipEntry</c> for the
		///   given file name and directory path, if it exists, and then calling <see
		///   cref="AddEntry(String,OpenDelegate, CloseDelegate)" />.  See the
		///   documentation for that method for further explanation.
		/// </remarks>
		///
		/// <param name="entryName">
		///   The name, including any path, to use within the archive for the entry.
		/// </param>
		///
		/// <param name="opener">
		///  the delegate that will be invoked to open the stream
		/// </param>
		/// <param name="closer">
		///  the delegate that will be invoked to close the stream
		/// </param>
		///
		/// <returns>The <c>ZipEntry</c> added or updated.</returns>
		///
		public ZipEntry UpdateEntry(string entryName, OpenDelegate opener, CloseDelegate closer)
		{
			RemoveEntryForUpdate(entryName);
			return AddEntry(entryName, opener, closer);
		}


		/// <summary>
		///   Updates the given entry in the <c>ZipFile</c>, using the given stream as
		///   input, and the given filename and given directory Path.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   Calling the method is equivalent to calling <c>RemoveEntry()</c> if an
		///   entry by the same name already exists, and then calling <c>AddEntry()</c>
		///   with the given <c>fileName</c> and stream.
		/// </para>
		///
		/// <para>
		///   The stream must be open and readable during the call to
		///   <c>ZipFile.Save</c>.  You can dispense the stream on a just-in-time basis
		///   using the <see cref="ZipEntry.InputStream"/> property. Check the
		///   documentation of that property for more information.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to the
		///   <c>ZipEntry</c> added.
		/// </para>
		///
		/// </remarks>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddEntry(string, System.IO.Stream)"/>
		/// <seealso cref="PickGold.Zip.ZipEntry.InputStream"/>
		///
		/// <param name="entryName">
		///   The name, including any path, to use within the archive for the entry.
		/// </param>
		///
		/// <param name="stream">The input stream from which to read file data.</param>
		/// <returns>The <c>ZipEntry</c> added.</returns>
		public ZipEntry UpdateEntry(string entryName, Stream stream)
		{
			RemoveEntryForUpdate(entryName);
			return AddEntry(entryName, stream);
		}


		private void RemoveEntryForUpdate(string entryName)
		{
			if (String.IsNullOrEmpty(entryName))
				throw new ArgumentNullException("entryName");

			string directoryPathInArchive = null;
			if (entryName.IndexOf('\\') != -1)
			{
				directoryPathInArchive = Path.GetDirectoryName(entryName);
				entryName = Path.GetFileName(entryName);
			}
			var key = ZipEntry.NameInArchive(entryName, directoryPathInArchive);
			if (this[key] != null)
				this.RemoveEntry(key);
		}




		/// <summary>
		///   Add an entry into the zip archive using the given filename and
		///   directory path within the archive, and the given content for the
		///   file. No file is created in the filesystem.
		/// </summary>
		///
		/// <param name="byteContent">The data to use for the entry.</param>
		///
		/// <param name="entryName">
		///   The name, including any path, to use within the archive for the entry.
		/// </param>
		///
		/// <returns>The <c>ZipEntry</c> added.</returns>
		public ZipEntry AddEntry(string entryName, byte[] byteContent)
		{
			if (byteContent == null) throw new ArgumentException("bad argument", "byteContent");
			var ms = new MemoryStream(byteContent);
			return AddEntry(entryName, ms);
		}


		/// <summary>
		///   Updates the given entry in the <c>ZipFile</c>, using the given byte
		///   array as content for the entry.
		/// </summary>
		///
		/// <remarks>
		///   Calling this method is equivalent to removing the <c>ZipEntry</c>
		///   for the given filename and directory path, if it exists, and then
		///   calling <see cref="AddEntry(String,byte[])" />.  See the
		///   documentation for that method for further explanation.
		/// </remarks>
		///
		/// <param name="entryName">
		///   The name, including any path, to use within the archive for the entry.
		/// </param>
		///
		/// <param name="byteContent">The content to use for the <c>ZipEntry</c>.</param>
		///
		/// <returns>The <c>ZipEntry</c> added.</returns>
		///
		public ZipEntry UpdateEntry(string entryName, byte[] byteContent)
		{
			RemoveEntryForUpdate(entryName);
			return AddEntry(entryName, byteContent);
		}


		//         private string DictionaryKeyForEntry(ZipEntry ze1)
		//         {
		//             var filename = SharedUtilities.NormalizePathForUseInZipFile(ze1.FileName);
		//             return filename;
		//         }


		/// <summary>
		///   Adds the contents of a filesystem directory to a Zip file archive.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   The name of the directory may be a relative path or a fully-qualified
		///   path. Any files within the named directory are added to the archive.  Any
		///   subdirectories within the named directory are also added to the archive,
		///   recursively.
		/// </para>
		///
		/// <para>
		///   Top-level entries in the named directory will appear as top-level entries
		///   in the zip archive.  Entries in subdirectories in the named directory will
		///   result in entries in subdirectories in the zip archive.
		/// </para>
		///
		/// <para>
		///   If you want the entries to appear in a containing directory in the zip
		///   archive itself, then you should call the AddDirectory() overload that
		///   allows you to explicitly specify a directory path for use in the archive.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to each
		///   ZipEntry added.
		/// </para>
		///
		/// </remarks>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddItem(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.AddFile(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateDirectory(string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.AddDirectory(string, string)"/>
		///
		/// <overloads>This method has 2 overloads.</overloads>
		///
		/// <param name="directoryName">The name of the directory to add.</param>
		/// <returns>The <c>ZipEntry</c> added.</returns>
		public ZipEntry AddDirectory(string directoryName)
		{
			return AddDirectory(directoryName, null);
		}


		/// <summary>
		///   Adds the contents of a filesystem directory to a Zip file archive,
		///   overriding the path to be used for entries in the archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   The name of the directory may be a relative path or a fully-qualified
		///   path. The add operation is recursive, so that any files or subdirectories
		///   within the name directory are also added to the archive.
		/// </para>
		///
		/// <para>
		///   Top-level entries in the named directory will appear as top-level entries
		///   in the zip archive.  Entries in subdirectories in the named directory will
		///   result in entries in subdirectories in the zip archive.
		/// </para>
		///
		/// <para>
		///   For <c>ZipFile</c> properties including <see cref="Encryption"/>, <see
		///   cref="Password"/>, <see cref="SetCompression"/>, <see
		///   cref="ProvisionalAlternateEncoding"/>, <see cref="ExtractExistingFile"/>,
		///   <see cref="ZipErrorAction"/>, and <see cref="CompressionLevel"/>, their
		///   respective values at the time of this call will be applied to each
		///   ZipEntry added.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		/// <para>
		///   In this code, calling the ZipUp() method with a value of "c:\reports" for
		///   the directory parameter will result in a zip file structure in which all
		///   entries are contained in a toplevel "reports" directory.
		/// </para>
		///
		/// <code lang="C#">
		/// public void ZipUp(string targetZip, string directory)
		/// {
		///   using (var zip = new ZipFile())
		///   {
		///     zip.AddDirectory(directory, System.IO.Path.GetFileName(directory));
		///     zip.Save(targetZip);
		///   }
		/// }
		/// </code>
		/// </example>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.AddItem(string, string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.AddFile(string, string)"/>
		/// <seealso cref="PickGold.Zip.ZipFile.UpdateDirectory(string, string)"/>
		///
		/// <param name="directoryName">The name of the directory to add.</param>
		///
		/// <param name="directoryPathInArchive">
		///   Specifies a directory path to use to override any path in the
		///   DirectoryName.  This path may, or may not, correspond to a real directory
		///   in the current filesystem.  If the zip is later extracted, this is the
		///   path used for the extracted file or directory.  Passing <c>null</c>
		///   (<c>Nothing</c> in VB) or the empty string ("") will insert the items at
		///   the root path within the archive.
		/// </param>
		///
		/// <returns>The <c>ZipEntry</c> added.</returns>
		public ZipEntry AddDirectory(string directoryName, string directoryPathInArchive)
		{
			return AddOrUpdateDirectoryImpl(directoryName, directoryPathInArchive, AddOrUpdateAction.AddOnly);
		}


		/// <summary>
		///   Creates a directory in the zip archive.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   Use this when you want to create a directory in the archive but there is
		///   no corresponding filesystem representation for that directory.
		/// </para>
		///
		/// <para>
		///   You will probably not need to do this in your code. One of the only times
		///   you will want to do this is if you want an empty directory in the zip
		///   archive.  The reason: if you add a file to a zip archive that is stored
		///   within a multi-level directory, all of the directory tree is implicitly
		///   created in the zip archive.
		/// </para>
		///
		/// </remarks>
		///
		/// <param name="directoryNameInArchive">
		///   The name of the directory to create in the archive.
		/// </param>
		/// <returns>The <c>ZipEntry</c> added.</returns>
		public ZipEntry AddDirectoryByName(string directoryNameInArchive)
		{
			// workitem 9073
			ZipEntry dir = ZipEntry.CreateFromNothing(directoryNameInArchive);
			dir._container = new ZipContainer(this);
			dir.MarkAsDirectory();
			dir.AlternateEncoding = this.AlternateEncoding;  // workitem 8984
			dir.AlternateEncodingUsage = this.AlternateEncodingUsage;
			dir.SetEntryTimes(DateTime.Now, DateTime.Now, DateTime.Now);
			dir.EmitTimesInWindowsFormatWhenSaving = _emitNtfsTimes;
			dir.EmitTimesInUnixFormatWhenSaving = _emitUnixTimes;
			dir._Source = ZipEntrySource.Stream;
			//string key = DictionaryKeyForEntry(dir);
			InternalAddEntry(dir.FileName, dir);
			AfterAddEntry(dir);
			return dir;
		}



		private ZipEntry AddOrUpdateDirectoryImpl(string directoryName,
												  string rootDirectoryPathInArchive,
												  AddOrUpdateAction action)
		{
			if (rootDirectoryPathInArchive == null)
			{
				rootDirectoryPathInArchive = "";
			}

			return AddOrUpdateDirectoryImpl(directoryName, rootDirectoryPathInArchive, action, true, 0);
		}


		internal void InternalAddEntry(String name, ZipEntry entry)
		{
			_entries.Add(name, entry);
			_zipEntriesAsList = null;
			_contentsChanged = true;
		}



		private ZipEntry AddOrUpdateDirectoryImpl(string directoryName,
												  string rootDirectoryPathInArchive,
												  AddOrUpdateAction action,
												  bool recurse,
												  int level)
		{
			if (Verbose)
				StatusMessageTextWriter.WriteLine("{0} {1}...",
												  (action == AddOrUpdateAction.AddOnly) ? "adding" : "Adding or updating",
												  directoryName);

			if (level == 0)
			{
				_addOperationCanceled = false;
				OnAddStarted();
			}

			// workitem 13371
			if (_addOperationCanceled)
				return null;

			string dirForEntries = rootDirectoryPathInArchive;
			ZipEntry baseDir = null;

			if (level > 0)
			{
				int f = directoryName.Length;
				for (int i = level; i > 0; i--)
					f = directoryName.LastIndexOfAny("/\\".ToCharArray(), f - 1, f - 1);

				dirForEntries = directoryName.Substring(f + 1);
				dirForEntries = Path.Combine(rootDirectoryPathInArchive, dirForEntries);
			}

			// if not top level, or if the root is non-empty, then explicitly add the directory
			if (level > 0 || rootDirectoryPathInArchive != "")
			{
				baseDir = ZipEntry.CreateFromFile(directoryName, dirForEntries);
				baseDir._container = new ZipContainer(this);
				baseDir.AlternateEncoding = this.AlternateEncoding;  // workitem 6410
				baseDir.AlternateEncodingUsage = this.AlternateEncodingUsage;
				baseDir.MarkAsDirectory();
				baseDir.EmitTimesInWindowsFormatWhenSaving = _emitNtfsTimes;
				baseDir.EmitTimesInUnixFormatWhenSaving = _emitUnixTimes;

				// add the directory only if it does not exist.
				// It's not an error if it already exists.
				if (!_entries.ContainsKey(baseDir.FileName))
				{
					InternalAddEntry(baseDir.FileName, baseDir);
					AfterAddEntry(baseDir);
				}
				dirForEntries = baseDir.FileName;
			}

			if (!_addOperationCanceled)
			{

				String[] filenames = Directory.GetFiles(directoryName);

				if (recurse)
				{
					// add the files:
					foreach (String filename in filenames)
					{
						if (_addOperationCanceled) break;
						if (action == AddOrUpdateAction.AddOnly)
							AddFile(filename, dirForEntries);
						else
							UpdateFile(filename, dirForEntries);
					}

					if (!_addOperationCanceled)
					{
						// add the subdirectories:
						String[] dirnames = Directory.GetDirectories(directoryName);
						foreach (String dir in dirnames)
						{
							// workitem 8617: Optionally traverse reparse points
#if SILVERLIGHT
#elif NETCF
                            FileAttributes fileAttrs = (FileAttributes) NetCfFile.GetAttributes(dir);
#else
							FileAttributes fileAttrs = System.IO.File.GetAttributes(dir);
#endif
							if (this.AddDirectoryWillTraverseReparsePoints
#if !SILVERLIGHT
 || ((fileAttrs & FileAttributes.ReparsePoint) == 0)
#endif
)
								AddOrUpdateDirectoryImpl(dir, rootDirectoryPathInArchive, action, recurse, level + 1);

						}

					}
				}
			}

			if (level == 0)
				OnAddCompleted();

			return baseDir;
		}

	}

}
